A significant factor in aircraft engine competitiveness is the maximum thrust-to-weight ratio that an aircraft turbofan engine provides while remaining safely mounted to the aircraft and providing safe operation. The thrust-to-weight ratio can be improved by reducing the overall turbofan engine weight without affecting the engine thrust. Therefore, identifying contributors to overall turbofan engine weight that may be redesigned while maintaining safe turbofan engine operation is desirable.
One contributor to overall turbofan engine weight is the multiple assembly interfaces, and another contributor is the front frame structure. Externally, an aircraft turbofan engine generally appears as an aerodynamically streamlined outer covering surrounding the bulk of the aircraft engine core. Internally, an aircraft turbofan engine typically includes multiple stages of components coupled via multiple assembly interfaces.
Each assembly interface generally comprises two opposing flanges bolted together. The interfaces increase manufacture and assembly time, disrupt engine airflow and increase overall turbofan engine weight. Manufacture and assembly time is increased due to the additional piloting features and the associated tight manufacturing tolerances generally required for proper alignment. Even with proper alignment, each assembly interface introduces a step and/or gap that is disruptive to the airflow that occurs through stages of components referred to as “fan bypass components” (hereinafter referred to as the “bypass”). Each interface introduces additional material and components, contributing to the overall turbofan engine weight and cost.
The front frame structure is a significant contributor to overall turbofan engine weight. The front frame structure is located forward of, and coaxial with, the turbofan engine core, and satisfies several purposes; two purposes of the front frame structure are directing air and providing structural strength. As an aerodynamic turbofan engine component, the front frame structure, located within the bypass, is designed to split incoming air (generally from a fan assembly) and direct it into either the engine core or the bypass. As a structural support, the front frame structure provides structural strength for attaching the engine to the aircraft, and for supporting the majority of engine-to-aircraft weight. Due to the extensive structural and weight-bearing duties of the front frame structure, it is typically formed with heavy, integrated, circumferential rings requiring complex manufacturing techniques and installation procedures.
Accordingly, an architectural design improvement that combines fan bypass components and the front frame structure is desirable. The desired system and method combines fan bypass components and minimizes assembly interfaces in a turbofan engine. The desired system and method further provides a front frame structure of reduced weight that slidably installs/removes from within the combined fan bypass components.